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Toward Understanding the Catalytic Synergy in the Design of Bimetallic Molecular Sieves for Selective Aerobic Oxidations

2013; American Chemical Society; Volume: 135; Issue: 8 Linguagem: Inglês

10.1021/ja3119064

1943-2984

Rebecca M. Leithall, Vasudev N. Shetti, Sara Maurelli, Mario Chiesa, Enrica Gianotti, Robert Raja,

Oxidative Organic Chemistry Reactions

Structure-property correlations and mechanistic implications are important in the design of single-site catalysts for the activation of molecular oxygen. In this study we rationalize trends in catalytic synergy to elucidate the nature of the active site through structural and spectroscopic correlations. In particular, the redox behavior and coordination geometry in isomorphously substituted, bimetallic VTiAlPO-5 catalysts are investigated with a view to specifically engineering and enhancing their reactivity and selectivity in aerobic oxidations. By using a combination of HYSCORE EPR and in situ FTIR studies, we show that the well-defined and isolated oxophilic tetrahedral titanium centers coupled with redox-active VO(2+) ions at proximal framework positions provide the loci for the activation of oxidant that leads to a concomitant increase in catalytic activity compared to analogous monometallic systems.